Insulin Therapy and Falls Due to Orthostatic Hypotension

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In the proposed study, the investigators examine in older adults with Type 2 diabetes the impact of beginning insulin therapy on the orthostatic drop in blood pressure as well as the response of arterial blood pressure and Doppler measures of cerebral blood flow during upright tilt. The investigators hypothesize that in older adults with Type 2 diabetes, the cardiovascular effects of insulin would precipitate or worsen orthostatic intolerance not present at baseline.

Condition or disease

Intervention/treatment

Orthostatic HypotensionDiabetesSyncope

Other: InsulinOther: No Insulin

Detailed Description:

Before and 2 weeks after the start of standard insulin therapy several tests will be done:

orthostatic hypotension will be tested for with 3 orthostatic maneuvers

vasovagal syncope will be tested with 2 tilt table tests, one augmented with 400ug of nitroglycerin

MCA velocity will be measured with a transcranial doppler

Heart Rate and Blood Pressure will be measured throughout the test with a Finometer and Power Lab on a beat to beat basis

Study sessions will occur before the initiation of insulin therapy (no insulin). Initiation of insulin administration will be determined as part of standard of care by the subjects diabetologist in the VGH Diabetes Centre and not as part of participation in this study.

Other: No Insulin

Study session will occur prior to initiation of insulin therapy.

After Initiation of Insulin Therapy

Study session will take place 2-4 weeks after the initiation of insulin therapy. Initiation of insulin administration will be determined as part of standard of care by the subjects diabetologist in the VGH Diabetes Centre and not as part of participation in this study.

Other: Insulin

Initiation of insulin administration will be determined as part of standard of care by the subjects diabetologist in the VGH Diabetes Centre and not as part of participation in this study.

2. The presence or absence of a positive augmented tilt table test [ Time Frame: 1 day ]

The augmented tilt table test will occur after receiving 300 μg nitroglycerin (GTN), and is a recognized method of testing for risk of vasovagal syncope. The tilt table will be considered positive and aborted prior to the 20 minutes if the subjects have a syncopal spell or demonstrate presyncopal (lightheadedness) symptoms in association with a 30 mm Hg drop in systolic blood pressure.

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Ages Eligible for Study:

65 Years and older (Adult, Senior)

Sexes Eligible for Study:

All

Accepts Healthy Volunteers:

No

Criteria

Inclusion Criteria:

All subjects must be 65 years of age or older

All must have been diagnosed with Type 2 diabetes for at least 5 years

All subjects must be insulin-naïve on recruitment

All subjects must be eligible to start insulin therapy (long or intermediate acting) as determined by their diabetologist

Exclusion Criteria:

Anemia, as determined by serum hematocrit

Abnormal liver function tests

Elevated creatinine

Smoker

Musculoskeletal or neurological condition that would preclude tilt table testing or orthostatic vitals